1. Field of the Invention
The present invention relates generally to computer-implemented graphics systems, and in particular, to a method, apparatus, and article of manufacture for providing visualization techniques for constructive systems for objects in a computer-implemented graphics system.
2. Description of the Related Art
The use of computer-implemented graphics programs is well known in the art. In typical graphics programs, such as AutoCAD(trademark), there are generally two geometric grids for assisting users in constructing or placing elements. These are static regular Cartesian or Polar projection grids, based either on a world origin or a local reference origin, or in advanced systems automatically inferred from a relative object point of interest or element constructive base point. Additional assistant geometries may be provided as extensions and relationships between elements.
However, users also need assistant temporary geometries that are constructive in nature, i.e., that reflect a xe2x80x9cconstructive systemxe2x80x9d. Constructive systems are important in the real world, especially for manufactured assemblies. For example, a stack of bricks is a simple three-dimensional (3D) constructive system, wherein the stack usually includes constraints on the size of individual bricks, as well as longitudinal constraints regarding the placement and assembly of individual bricks into the stack Alternatively, an arch comprised of bricks may be a complex 3D constructive system, wherein the arch includes constraints on the size of individual bricks, 3D placement of the bricks, attachment of the bricks, etc. The issues become even more complex when dealing with other complex assemblies of objects.
Another problem arises, however, in that such 3D constructive systems use a two-dimensional (2D) graphical user interface (GUI) to display graphical images, such as 2D or 3D models, schematic diagrams, photorealistic images, etc. When a 3D space is displayed in a 2D GUI, the operator is responsible for perceiving the third dimension, and is often aided by perspective views, rendering, shadows or other visual cues provided by the graphics systems.
Consequently, there is a need in the art for improved techniques for providing visual cues in computer-implemented graphics systems to navigate objects constrained by constructive systems through a 3D world space using only a 2D viewport. Specifically, there is a need in the art for improved visualization techniques for constructive systems in computer-implemented graphics systems.
To address the requirements described above, the present invention discloses a method, apparatus, and article of manufacture for providing visual cues for navigating a three-dimensional space. A two-dimensional viewport of the three-dimensional space is displayed on a monitor attached to the computer, and an object is moved through the two-dimensional viewport of the three-dimensional space according to a position of the input device attached to the computer. A graphical image of the object is created using constructive geometric data stored therein, wherein the constructive geometric data identifies at least one constructive system, and the constructive system identifies at least one constraint on the processing of the object. The graphics system determines a position of the object within the three-dimensional space relative to the two-dimensional viewport, and generates one or more visual cues to indicate the position.